Cut pile type synthetic turf simulating grass



Dec. 29, 1970 E, p CARTER ETAL 3,551,263

CUT PILE TYPE SYNTHETIC TURF SIMULATING GRASS Filed Jan. 24, 1968 FIG.2.

FIG. I.

FIG. 3.

FIG. 6.

INVENTORS ERNEST P. CARTER CHILTON TI VEST ATTORNEY United States PatentO 3,551,263 CUT PILE TYPE SYNTHETIC TURF SIMULATING GRASS Ernest P.Carter, Durham, N.C., and Chilton T. Vest, Decatur, Ala., assignors toMonsanto Company, St.

Louis, Mo., a corporation of Delaware Filed Jan. 24, 1968, Ser. No.700,235 Int. Cl. A41g 1/00 US. Cl. 161-21 21 Claims ABSTRACT OF THEDISCLOSURE Synthetic grass products of improved quality are produced byconventional tufting of braided ribbons characterized by substantiallyrectangular cross sections, by conventional carpet Weaving or knittingtechniques, or by otherwise securing braided ribbons to a backing.

BACKGROUND OF THE INVENTION This invention relates to an improvedsynthetic turf which simulates grass. More particularly, this inventionrelates to a grass-like turf useful both indoors and outdoors for avariety of recreational and sports activities.

Recent developments in the art of producing synthetic turf have includedthe discovery that a surface cover or turf consisting of aweather-resistant backing and relatively heavy denier cut pile ribbons,having substantially rectangular cross sections, secured therein with asuitable latex, closely simulates grass and is not adversely affected byexposure to all types of weather conditions and a-busive wear. It wasfound that such turfs retain their grasslike appearance remarkably wellfor long periods of continued use as a cover for playgrounds. Many ofthe performance characteristics of such monofilament turf are comparablewith those possessed by natural turf.

These flat-filament turfs were produced for the most part byconventional weaving, knitting or tufting operations employing either asingle ribbon or a yarn of twisted ribbons.

Difliculties were encountered in tufting the twisted ribbon yarn.Ribbons having cross sections substantially rectangular in shape, whentwisted into yarn, were unorganized and had a tendency to knot andtangle in the guide bars and needles of conventional tufting machines.Moreover, it was found that the filaments tend to line up or stack oneach side of the needle during the tufting process, thereby creating inthe tuft, a lined or stacked appearance in the relationship ofindividual fibers one to another.

It has also been found that even where the above described difiicultiesin using fiat filament ribbons in conventional tufting machines are notinvolved, as where the product is produced by conventional carpetweaving or knitting techniques, or where the ribbons are secured in anyother manner to the backing, the use of the braided ribbons provides amore uniform filament emergence pattern from the backing than wheretwisted flat filaments are employed.

SUMMARY OF THE INVENTION It is an object of the instant invention toprovide in a cut pile type synthetic turf, with filaments havingsubstantially rectangular cross sections, a pile in which the filamentsare not lined up or stacked as they emerge together from the backing,but ratheropen up or bloom generally in a circular manner.

It is a second object of this invention to provide a method for theproduction of synthetic grass-like turf of superior quality fromsynthetic filaments having generally rectangular cross sections.

It is still another object of this invention to provide a method ofpreparation of a yarn consisting of filaments having a substantiallyrectangular cross section, suitable for conventional cut-pile tufting inthe production of synthetic turf.

Briefly, the objects of this invention are accomplished by conventionalbraiding of from 4 to 8 filaments having substantially rectangular crosssections, preferably characterized by widths of at least three timesgreater than their thickness, into a yarn, and by conventional cutpiletufting, weaving, knitting or otherwise securing said yarn to form astructure consisting of a backing having a suitably latex formulation onthe other surface of the where tufting, knitting, or Weaving isemployed, applying a suitably latex formulationon the othe rsurface ofthe backing to render the complete structure dimensionally stable. Apolymeric elastomer may then be applied to the latex backing to providea more stable and improved structure.

Other objects and advantages of the invention will be apparent from thedetailed specification and the following drawing in which,

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of abraided yarn suitable for use in accordance with the instant invention;

FIG. 2 is a section through the eye of a conventional tufting needleshowing a braided yarn as in FIG. 1 therein;

FIG. 3 is a cross section of a conventional tufting needle with twistedyarn passing through the needle eye;

FIG. 4 is a schematic perspective view from overhead of the emergence ofthe free, individual filaments from the braided construction whichremains intact in and adjacent to the backing;

FIG. 5 is a schematic perspective view from overhead of the emergence ofa twisted yarn as shown in FIG. 3; and

FIG. 6 is a cross sectional view of a synthetic turf produced byconventional methods using the braided yarn shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The grass-like pile or facematerial of this invention normally consists of extruded monofilamentsof from about 200 to 1200 denier, and preferably of from about 300 to500 denier, the denier decreasing as the number of braided filaments isincreased from a minimum of about 4 to a practical maximum of about 8.As the number of filaments per tuft is increased, and the denier of thefilament is decreased, the characteristics of the turf will vary fromthat of a coarser grass to that of a finer grass.

The filaments are extruded from polyamides, polyesters, andpolypropylene, but preferably the polyamides which nylon 66, nylon 6,nylon 4, nylon 610, nylon 11 and their filament forming copolymers. Thefilaments should be generally fiat and ribbon-like to simulate naturalgrass and possess suitable bending properties. If preferred, the

filament surfaces may be delustered to reduce the sheen produced by thefiat surfaces of the ribbons. One means for accomplishing this is toimpart to the ribbon longitudinal striations during the extrusionprocess. Filaments having round, oval, arcuate, or other cross-sectionalconfigurations can be used but are not very suitable primarily becauseof their stillness and unwillingness to bend. It has been demonstratedthat a ribbon-like filament extruded from a rectangular, slotted orificedimensioned to produce monofilament ribbon having a thickness of between0.001 and 0.003 inch, and a Width of between 0.01 and 0.20 inch ispreferred for the product of this invention since ribbons having thesecross-sectional dimensions possess good flexing and bendingcharacteristics which promote its usefulness as a substitute for naturalgrass turf. If found advantageous, the ribbons may be treated withsurfactants or other means for roughing the surface to facilitatefabrication thereof and prevent foot-wear slippage. The ribbon should bedrawn and treated to provide the physical properties desired dependingupon the polymer composition and the utilization planned for the turf.Preferably, the thermoplastic material is pigmented green to simulatethe color of grass, although other colors may be used for specialeffects. Multifilament single strand ribbons have been utilized, butwithout success, because the filaments comprising the strands becomeseparated when they are subjected to the conditions as contemplated forthe produce of the present invention.

It is known that the addition of certain pigments to thermoplasticmaterials such as nylon and polyester may increase its resistance todegradation by ultraviolet light although many pigments, particularlyinorganic materials, tend to accelerate such degradation. We have foundthat a mixture of about 0.50 percent of a phthalocyanine green and 1.50percent of a cadmium yellow based on polymer weight provides good colordepth and sufficient stabilization against ultraviolet light for mostapplications.

Phthalocyanine green refers to the well-known chlorinated copperphthalocyanine chelate compounds widely used as colorants; for examples,Monastral Green and Mapaco Green pigments made by E. I. du Pont deNemours, Pagment Department, Wilmington, Del. Cadmium Lithopone yellowdesignates the common yellow inorganic pigments consisting principallyof cadmium sulfide. The cadmium yellow pigments supplied by the GliddenCompany, Baltimore, Md. and by Kentucky Color Company, Louisville, Ky.,have proven quite satisfactory.

If desired, the nylon may be further stabilized by the incorporation ofany of a number of well known UV absorbers which are compatible with theresin. These include such compounds as the aryl esters of phosphoricacid, the alkaryl phosphinates, zinc phosphates, manganous salts,chromium salts, and copper salts. For optimum weather resistanceproperties the nylon ribbons should be placed under the minimum tensionpossible.

The backing material may be formed with fibers prepared from polyesters,polyacrylonitrile, polypropylene and nylon but preferably polyesters andpolyacrylonitrile. Formation of the backing may be accomplished byweaving and knitting or any of the known processes for preparingnon-Wovens, particularly needle punching. The backing fibers arepreferably green solution dyed to add color depth to the turf and thusenhance the grass-like appearance thereof where this result is desired;however, white or conventionally dyed fibers of green or other colorsmay be employed. For turf which will be used outdoors the arcylic fibersare preferred because of their excellent weather-resistant properties.Turfs made for indoor installation are preferably constructed frombacking formed from polyester fibers because they possess betterstrength properties than the acrylic fibers. Of course nylon fibers arestronger than polyester fibers, but the stretch characteristics of nylonfibers make them less desirable for most purposes.

An example of a suitable tufting medium or hocking fabric is a 5 to 10ounces per yard nylon scrim reinforced needle punched fabric formed fromacrylic staple fibers which has been treated with about 1.5 ounces persquare yard of an 80/20 mixture of Hycar 1571 Resloom M-80 resin. Hycar1571 is a water emulsion of butadiene-acrylonitrile copolymer sold by B.F. Goodrich Chemical Co., Cleveland, Ohio, and Resloom M-80 is amelamineformaldehyde resin sold by Monsanto Co., St. Louis, Mo.

Another backing material suitable for tufting is a nylon scrimreinforced polyurethane foam carpet backing which is marketed under thetrademark, Chemback, by the 4 Chemstrand Co., Division of Monsanto Co.Chemback is comprised of an open-mesh woven nylon scrim coated withfoamed polyurethane having a density of approximately 2 lbs. per cubicfoot. Chemback is produced in thickness of approximately 0.06 to 0.10inch and in weights of 3 to 6 ounces per square yard.

Braiding of the filaments may be accomplished on any conventionalbraiding machine designed to accommodate from 4 to about 8 carriers. Thedesired flexibility of the braided yarn for conventional tufting makesit preferably that no central filament be included in the braid when itis subjected to tufting.

Any conventional tufting technique may be used with the braidedfilaments. When tension is applied to the braided yarn by the machineduring tufting, all of the ends pull together into a tight yarn whicheasily passes through the machine elements.

Conventional carpet weaving and knitting techniques may also be used asmay any other method of securing the face ribbon to a backing.

After weaving, knitting or tufting the face ribbon with the backing toproduce a turf fabric, a solution of latex or the like is applied to theback of the fabric by padding or other acceptable means. The latexprovides dimensional stability to the fabric and also serves to anchorthe ribbons in the backing material. It must therefore be of acomposition which has good adhesion to both the synthetic ribbon and thesynthetic backing material. One such latex composition is a dispersionof Lotol 7562, Pyratex, Dow Corning Antiform, and Alcogum.

A typical latex formulation suitable for use in this invention consistsof by weight:

Lotol 7562 is a compounded natural rubber latex sold by the NaugatuckChemical Division of U.S. Rubber, Naugatuck, Conn.; Pyratex is a vinylpyridene terpolymer also sold by Naugatuck Chemical; Dow CorningAntifoam is a silicone oil sold by Dow Corning, Midland, Mich.; andAlcogum is a sodium polyacrylate viscosity control agent sold by AlcoChemical Corp., Philadephia, Pa.

The Lotol, Pyratex, and Antifoam are combined and agitated to preparethe latex composition. The Alcogum is added to the mixture until theviscosity of the solution is increased to about 2000 cp. on theBrookfield viscometer. Between about 2 and 6 ounces per square yardbased on solids of the latex solution is padded or otherwise applied tothe backing fabric of the turf. The latex is dried and then cured atabout 325 F. for .5 minutes.

After applying and curing the latex, the turf is dimensionally stableand may be employed as a useful product without further treatment.However, it has been found that the Wear properties of the turf areenhanced if a resilient foam backing is applied before use. For outdoorapplications, a PVC (polyvinylchloride) closed cell foam or solid PVC ispreferred because of its excellent strength and well known weatherresisting properties. An open cell PVC foam is suitable for indoor usesbut generally is not desirable for outdoor installation because of itspropensity to absorb large amounts of moisture. However, if the turf isgoing to be used indoors, other elastomers such as latex foam andpolyurethane also may be used with good results.

The foam may be applied by any of the conventional techniques which arewell known in the art. Either mechanical, physical, or chemical foamingmay be employed, and the foam sheet may be either cast and cureddirectly on the back of the turf, or cast separately and cemented inplace. The foam may be any thickness and density desired, but generallya PVC foam between /6 and inch thick and having a density of to 55pounds per cubic foot is preferred. A polyurethane foam of a similarthickness having a density of 1.0 to 4.0 pounds per cubic foot andreinforced with an embedded nylon scrim is also satisfactory. It isnoted however that for a preferred embodiment of this invention, a PVCplastisol containing a foam stabilizer is frothed with latex foamingequipment and cast directly upon the turf to form an open cell foamhaving a thickness of inch and a density of about 35 pounds per cubicfoot.

Using the above procedures, a synthetic turf is produced with a virtualabsence of any lined effect such as is common in most tufted products. Arandomness or lack of uniformity of the position of blades as theyemerge from the backing is also achieved. Braided yarns of this type offilament not only produce a better coverage of the backing aftertufting, but the cut piles open with ease completely without the effectof any setting or kinking resulting from the twist.

Referring now in detail to the drawing, FIG. 1 shows a typically braidedyarn of 8 filaments each having a generally rectangular cross sectioncharacterized by a Width more than 3 times greater than its thickness,which is suitable for conventional tufting, weaving or knitting inaccordance with the instant invention and for the production of asynthetic grass of improved quality. FIG. 2 shows filament braid 1 inthe eye of tufting needle 2, and FIG. 3 shows the braid being under sometension as would be encountered during the conventional tufting process.FIG. 4 depicts schematically the emergence arrangement of the freeunbraided pile ribbon ends of a tufted braid of 4 filaments 3 from abacking not shown. FIG. 6 shows a cross section of the completed cutpile synthetic turf product showing the emergence of filaments 3 fromfiber backing 4, the pile being anchored securely therein by bondingagent 5. A polyvinyl chloride foam 6 has been applied on to the backingto improve the physical properties of the turf.

The invention will be more easily understood from the followingexamples, which are meant to be illustrative but not limited. In theseexamples, parts and percentages are by weight unless otherwisespecified.

EXAMPLE I Fat monofilament ribbons were produced by the conventionalmelt extrusion method with standard screw extruder and auxiliaries. Thepolypropylene polymer identified as Escon 107, Grade CD 70, was suppliedby Enjoy Chemical Company, New York, NY. A mixture of 1.4 percentcadmium yellow pigment and 0.6 percent phthalocyanine green pigment wasincorporated in the polypropylene at the extruder inlet. The resultantgrassgreen filaments were 0.030 inch wide by 0.0018 inch thick. Thesepolypropylene filaments were braided into an 8 ply braid which wastufted into a nylon scrim reinforced polyurethane foam tufting mediumand sheared to /2 pile height. A latex adhesive was applied to theunderside of a portion of the fabric and a non-woven rayon-polyolefinscrim was applied to the adhesive to form a secondary backing. Sampleswere found to have good random orientation of individual filaments, aminimum of lining, as well as excellent durability.

EXAMPLE II Analogous to the procedure described in Example I, the sametype of pigment composition and extrusion system was used to producegrass-green polyethylene terephthalate ribbon monofilaments 0.045 inchwide by 0.0015 inch thick. The polyester polymer was supplied by theChemical Division of Goodyear Tire & Rubber Company, and was designatedVFR 130l-A. A four ply braided yarn of polyester filaments was tuftedinto a nylon scrim reinforced polyurethane foam tufting medium, and thetufts were cut to /2" pile height. A thin layer of adhesive latex wasapplied to the under side to bond the fabric to a pad of foamed PVC A"thick.

EXAMPLE III A synthetic nylon turf was produced according to theprocedure of Example I using 900 denier nylon filament ribbonsapproximately 0.002" thick by 0.066 wide which was braided into a 4 plybraid. The facing had a pile height of A.

EXAMPLE IV A synthetic nylon turf was produced by tufting a 6 ply braidof 500 denier nylon filament ribbons into a backing of thick sheet ofpolyurethane foam which was reinforced by a nylon scrim. The tufts werecut to form a turf with a pile height of and the back of the fabric waslatexed to firmly anchor the nylon and prevent shedding.

It will be apparent that the product of this invention, with its randomcircular emergence of individual filaments of a tuft, has a physicalappearance amazingly similar to that of natural grass turf, and mayconveniently be employed both indoors and outdoors as a substitute fornatural grass. The particular materials and their construction arecombined to produce a new and novel product which is suitable forsoft-shoe sports and cleated or spikedshoe sports. Performance testshave proved that the synthetic turf of the present invention hasball-bounce characteristics. somewhat similar to those of natural-grassturf.

For outdoor installations provisions must be made for adequate drainageof the synthetic turf. Depending upon local topography and type ofsubsurface, a slight slope may be sufiicient to remove water by simplesurface flow. In very fiat regions one of the more permeable orperforated backing materials is preferred to aid water seepage into thesubsoil. Synthetic turf according to the invention is not attacked bymildew or other fungi. Standing water in low areas should be avoided,however, since adventitious nutrient material may accumulate and supportfungal growth that produces surface discolorations which are sometimesdiflicult to remove.

While the invention has been described for general purpose use, it is tobe understood that certain modifications which will adapt the syntheticgrass to meet the specific requirements demanded for individualcircumstances are well within the concepts of this invention describedherein and therefore the scope is not to be limited except as set forthin the appended claims.

We claim:

1. A simulated grass-like product comprised of extruded thermoplasticmonofilament ribbons having substantially rectangular cross sections,said ribbons extending from and substantially perpendicular to a backingto which said ribbons are secured, from about 4 to about 8 of saidribbons being braided together at a point of emergence from the backing.

2. The product of claim 1 with said ribbons being tufted into saidbacking.

3. The product of claim 1 with said ribbons being woven into a warp andfill backing.

4. The product of claim 1 with said ribbons being knitted with thefibers of said backing.

5. A simulated grass-like tufted product comprised of extrudedthermoplastic monofilament ribbons having substantially rectangularcross sections and having a backing and a cut-pile face of unbraidedribbons, said ribbons being secured in the backing on the side oppositethe cutpile face, from about 4 to about 8 of said ribbons being braidedtogether where secured adjacent to and emerging from said backing.

6. The product of claim 5 having resilient material bonded to the sideof the backing having an adhesive applied thereon.

7. The product of claim in which the thermoplastic is nylon.

8. The product of claim 7 in which the nylon contains pigments.

9. The product of claim 5 in which the thermoplastic is polypropylene.

10. The product of claim 9 in which the polypropylene contains pigments.

11. The product of claim 5 in which the thermoplastic is polyethyleneterephthalate.

12. The product of claim 5 in which the ribbons have a denier of from300 to 900.

13. The product of claim 5 in which the braid consists of from about 4to about 8 of said monofilament ribbons.

14. A simulated grass-like tufted product comprised of extrudedthermoplastic monofilament ribbons and having a backing and a cut-pileface, said ribbons having substantially rectangular cross sections andbeing secured in the backing by an adhesive material applied to thebacking on the side opposite the cut pile face, the segment of saidribbons being secured in said backing being braided together, the freeends of said ribbons emerging from said backing as a pile in a generallyrandom bloom fashion.

15. The product of claim 14 having a resilient material bonded to theside of the backing having the adhesive applied thereon.

16. The product of claim 14 in which the thermoplastic is nylon.

17. The product of claim 16 in which the nylon contains pigments.

18. The product of claim 14 in which the thermoplastic is polypropylene.

19. The product of claim 18 in which the polypropylene containspigments.

20. The product of claim 14 in which the thermoplastic is polyethyleneterephthalate.

21. The product of claim 14 in which the ribbons have adenier of from300 to 900.

References Cited UNITED STATES PATENTS 3,332,828 7/1967 Faria et al.161-62X 2,913,803 11/1959 Dodds 16164UX 3,461,024 8/1969 Bloch 16165XPHILIP DIER, Primary Examiner U.S. Cl.X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, DatedDecember 29,

Inventor) Ernest P Carter et a1 It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 2, line 13, "a suitably latex formulation on the other surface ofthe" should read a cut pile face extendin, from one surface thereof and,line 15, "suitably" should read suitable line 55, after "which" insertinclude Column 3, line 64, "hocking" should read backing Colum 5, line1, "l/6" should read l/8 line 46, "Fat" should read Flat Signed andsealed this 4th day of ay. 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, Attesting OfficerCommissioner of Pate

